k24a4 frank
 

will a k24a4 and k20a2 head work without issues? valve clearence? do i need to do anything beside swap the head?

Yes it will work but you would have to change the rods and pistons due to the design of the pistons you will have valve to piston contact if they are not changed , to my knowlege the only block the k20a2 head will bolt up perfectly to without having to change the pistons is the k24a2 or a1.

so if i bought forged pistons and rods i would need the k24a2 ones and i would be good?

Yes sir